Optical isolator and method for making same

A method for manufacturing an optical isolator, the method comprising:

• providing an outer tube;
• providing a first optical collimator comprising a first ferrule with an optical fiber therein, and a first collimating lens, the first ferrule and the first collimating lens being secured in a first tube;
• attaching a first birefringent crystal to an end of the first collimating lens;
• attaching a Faraday rotator to the end of the first collimating lens;
• providing a second optical collimator comprising a second ferrule with an optical fiber therein, and a second collimating lens, the second ferrule and the second collimating lens being secured in a second tube;
• attaching a second birefringent crystal to an end of the second collimating lens;
• inserting the first tube together with the first birefringent crystal and Faraday rotator into a first end of the outer tube to a predetermined position, and fastening the first tube and the outer tube together;
• inserting the second tube into a second end of the outer tube to a predetermined position, and rotating the second collimator until an angle between optical axes of the first and second birefringent crystals is equal to an angle by which the Faraday rotator rotates light passing through the Faraday rotator;
• and
• fastening the second tube and the outer tube together.

An optical device comprising:

• an outer tube;
• opposite first and second collimators received within said outer tube in an axial direction thereof, said first collimator including a first ferrule and a first lens with a first birefringent crystal attached to an end of said first lens, said second collimator including a second ferrule and a second lens with a second birefringent crystal attached to an end of said second lens, said first birefringent crystal defining a first optic axis with an angle relative to a second optic axis defined by said second birefringent crystal;
• a Faraday rotator positioned between said first birefringent crystal and said second birefringent crystal with a magnetic ring circumferentially located thereabout;
• wherein
• via rotatably adjusting relative radial positions between the first collimator and the second collimator, the relative angle between the first optic axis and the second optic axis can be correspondingly altered, so that the device may be optimized to have lower insertion loss and higher isolation as an isolator, or performs as an attenuator in other applications.